1. Field of the Invention
The present invention relates generally to telecommunications systems and methods for placing wireless calls within a local area network based wireless telecommunications system using internet protocol routing procedures, and specifically to placing wireless calls within a local area network based wireless telecommunications system based upon the quality of service.
2. Background and Objects of the Present Invention
The first, Local Area Networks (LANs) were proprietary and developed to support unintelligent user workstations in which a primary station controlled the operations of the attached devices (secondary stations). The effectiveness of this technology decreased because the master/slave protocol was too slow and cumbersome. Therefore, new types of LANs were developed, such as Ethernet LANs and token-ring LANs. Ethernet LANs and token-ring LANs are designed for data applications and use a shared medium (bus or ring, respectively) designed for 10 Mbit/s speeds and up to Gigabit speeds.
However, during periods of high activity, the shared medium does not respond well to all users, which results in degraded response time and throughput. Therefore, Switched Ethernet LANs were developed to provide more capacity to the end users. Switched Ethernet does not rely on sharing the media. Instead, Switched Ethernet provides point-to-point bandwidth between the user station and a switch. Another type of LAN being developed alongside Switched Ethernet is the Asynchronous Transfer Mode (ATM) based LAN, which utilizes very high-speed ATM switches that support multimedia applications.
On top of these different networking architectures, such as Switched Ethernet or ATM, which define the physical attributes of the communications network, many LANs have begun using Internet Protocol (IP) to route data between hosts on the network. The data is routed in datagrams and is transmitted using connection-less network services. Therefore, IP does not guarantee the reliable delivery of the data or the sequencing of the datagram. Hence, an upper layer, such as Transmission Control Protocol (TCP) or User Datagram Protocol (UDP), must provide this function. TCP connection-oriented services provide reliable delivery of data between the host computers by establishing a connection before the applications send data. Thus, TCP guarantees that the data is error free and in sequence. On the other hand, UDP connection-oriented services are used by various applications to send messages where the integrity of the data is not as important.
Data can be sent across a LAN from an originating host computer to a receiving host computer using the IP routing protocol by encapsulating the data sent by the originating host computer into an IP datagram, which includes an IP header. The IP header identifies the address of the receiving host computer. The IP datagram and header can then be further encapsulated into the specific protocol of the transit network, such as an Ethernet LAN, for delivery of the IP datagram and header to an IP router.
After the transit network has delivered the IP datagram and header to the IP router, the IP router strips away the control information and uses the destination address in the datagram header to determine where to route the traffic. Typically, the IP router then passes the datagram back to the sub-network by invoking a sub-network access protocol, such as Ethernet on the LAN. This protocol is used to encapsulate the datagram header and user data into the headers and trailers that are used by the sub-network to deliver the data to the receiving host computer. It should be understood that routers can also be used to transport data to other LANs.
LANs not only interconnect computers for data communications, but can also interconnect mobile terminals for voice communications. This convergence of voice and data communications has allowed voice traffic to be sent over IP-based networks, which has, in turn, increased the total amount of traffic over these IP-based networks. For example, FIG. 1 depicts the implementation of a mobile communications system into a LAN 100. The mobile communications system includes an Access Node (AN) 130, which combines a Mobile Switching Center (MSC) functionality 134 for controlling calls made to and from Mobile Stations (MSs) 145 within the LAN 100 and a Base Station Controller (BSC) functionality 132 for controlling radio-related functions, such as channel assignment. The mobile communications system also includes at least one Base Transceiver Station (BTS) 140, which operates as a tranceiver for transmitting and receiving voice and control messages to and from the MSs 145, and an associated A-bis Gateway 142, which converts between circuit-switched signaling used by the BTS 140 and packet-switched signaling used by the LAN 100. The AN 130 and A-bis gateway 142 are connected to the LAN 100 through an LAN backbone 110.
The LAN 100 is managed through an LAN management system (LMS) 120 such as Tivoli or other similar system, which monitors the traffic and load on the LAN backbone 110. A gatekeeper 180 allocates bandwidth for all hosts, e.g., computers 125 and BTSs 140, on the LAN backbone 110 using, for example, the H.323 protocol. It should be noted that the LMS 120 can be included within the gatekeeper 180.
Wireless voice communications are transported through the LAN backbone 110 between BTSs 140 or between a BTS 140 and a Public Gateway (PG) 150 via UDP/IP. The PG 150 provides the interconnection between the packet based LAN 100 and the circuit switched public telephone network, e.g., Public Switched Telephone Network (PSTN) and Public Land Telephone Network (PLMN) 160. In many cases, a PLMN cell 192 overlaps the LAN 100. Speech and data are transmitted within the LAN 100 and through the Internet 175 using an IP Router 170.
In the IP based LAN wireless system 100, the BTSs 140 and the Access node 130 communicate with each other through the LAN backbone 110. In addition, the LAN backbone 110 is used by all other hosts 125, e.g., computers, in the network 100 to send and receive data communications between each other and through the Internet 175 via the IP Router 170. Therefore, when the LAN backbone 110 becomes congested, which can occur, for example, when a computer host 125 is downloading a large file, voice packets sent via the unreliable UDP can be lost, resulting in a decline in speech quality, and thus, poor Quality of Service (QOS) to MSs 145 sending and receiving the voice packets.
It is, therefore, an object of the present invention to broadcast QOS information based upon the congestion within the LAN to mobile stations within the LAN.
It is a further object of the present invention for mobile stations to use the QOS information in deciding whether to place a call on the IP based LAN.
It is still a further object of the present invention to allow mobile stations to complete calls on the traditional PLMN network or on another LAN when the QOS on the IP based LAN serving the mobile stations is poor.
The present invention is directed to telecommunications systems and methods for allowing a mobile station to determine whether or not to place a wireless call through an IP based LAN based upon broadcasted QOS information. The gatekeeper has access to the QOS information from the IP based LAN and periodically sends the QOS to the BSC functionality within the AN through the MSC functionality within the AN. The BSC functionality then transmits the QOS parameter on the System Information message via the BTS to the MSs served by the BTS. The MSs receive this QOS information and use this QOS information to decide upon a transport method to complete outgoing wireless calls, such as through the IP based LAN, through the PLMN or through another IP based LAN. Advantageously, by allowing MSs to decide whether to place calls on the IP based LAN based upon QOS information, the load on the IP based LAN can be reduced and adequate speech quality can be maintained. In addition, the IP based LAN can use this QOS information to differentiate charging for wireless calls.